The climate has changed radically at times when there was no extinction, and extinctions have occurred when the climate, at least roughly speaking, should have been benign. There is no question that there were catastrophic changes in temperature and probably in precipitation on many occasions in the past 100,000 years. We know that, for entirely natural reasons, temperature excursions of seven to 12 degrees Celsius occurred within that time period in the space of a century or less, which is basically 12 times the maximum rate of change in the last century of "global warming."

Me too. The problem as I see it is that humans were not present in large enough numbers to pass these diseases on over such a large area -- it breaks down for the same reason that he gives for the over-hunting hypothesis.

Not that it's completely out of line, however: the American Indians were practically wiped out within a few decades by various "pox" diseases.

I'm sceptical, but not entirely disbelieving of this. The humans wouldn't necessarily have had contact with all the animals. Just infect a few, who roam within their habitats, and infect others. Just like the Spaniards didn't travel all the way into the Continental US, but smallpox certainly did via trade routes. Good book on this subject btw...

Yes, it was humans. However, this might put the lie to the whole myth of the benevolent natives who did nature no harm until the white man appeared...On the downside, it would appear to assist the 'humans are evil no matter what' VHEMT goobers.

"SA: So, in your opinion, even if the first Americans were highly skilled hunters, could their population sizes and the population sizes of these animals have been such that overkill would even be plausible?

RM: The answer is no, by any scenario. I don't care how early you want people to get into the New World, thereís absolutely no evidence of a positive sort that they were there in huge numbers. In fact, it has to be the opposite, whereas the animals, in some cases, had distributions that were continent wide. Some of the ground sloths, for example, are known from as far south as Mexico and from as far north as the Yukon. The notion that people in whatever numbers and with whatever intent could have come in and slaughtered enough sloths in every possible habitat where they lived in numbers sufficient to cause their extinction--this is unbelievable to me.

Hell - He doesn't WANT to admit the possibility/probability that early man killed them off. (See, if that were so, then early man WASN'T the perfect little innocent twho loved nature and lived co-equally with until Columbus came along and polluted the whole continent with those evil, nasty, European capitalistic christian ideas of free enterprise.

I've seen the other figures that show easily that a small band, moving at less than 300-500 miles PER YEAR could kill every large animal population in only few thousand years (between the 12,000 BC arrival to the 9000 BC death. In doing so, they'ed only need kill a reasonable fraction of each population each year ... no more than done now in Africa by the early tribes there.

It was people. It's interesting to take a look at mega fauna worldwide, and place what happened to them.

Australia: Australia had several significant species of mega fauna. There was a wombat the size of a hippo. A nine foot tall kangaroo. And many others. They all died out 50,000--45,000 years ago. Human beings arrived in Australia about 50,000 years ago.

New Zealand: New Zealand had extremely large ostrich-like birds called moas as its mega fauna. If alive today, the largest moa woulds be twice the size of an African ostrich. Moas died out about 1,000 AD. Human beings arrived in New Zealand about 1,000 AD.

The Americas: Well, it has been posted above, but the mega fauna died out after the arrival of man, which is not really disputed.

Eurasia: Europe and Asia had mammoths and wooly rhinos, however, the genus homo has been living in Eurasia for 1/4 million years. The Indian elephant and rhinoceros still ives.

Africa: Africa still has most of its mega fauna. The genus homo evolved here. The case has been made, that as man evolved from skinny, hapless ape towards the world's most dangerous predator, the animals evolved along side man to build a natural fear of him. These seems to be the case with Africa/South Asia, which man has lived in far longer than anywhere else in the world. From there he spread nothward to Europe and Siberia. The mammoth and wolly rhinos home grounds (hmmm).

Since we have been homo spaiens sapiens, whenever we entered an entirely new area, the big meaty animals went extinct. I've also seen studies showing how only a moderately heavy predation of an animal species can have a sprial effect downward on that species survival, especially large animals that have few young that take years to reach adulthood. My vote still resides with (hungry) man the predator as the culprit.

Around 1110, in England, there was a very strange disease that killed all kinds of mammals and birds. No one knows what it was and it doesn't sound like any known disease. I read about it in an old book I have. Perhaps it was the same disease that caused the last mass extinction.

It never ceases to amaze me the lengths to which some politically correct scientists will go to deny the obvious. After all, they have to defend the myth of the American Indian as "noble, ecologically sensitive, soulful mystical types". They just can't admit that the sudden extinction of quite a few large mammal species in North America (horse, camel, mammoth, mastodon, giant sloth, etc.) coincided with the arrival of the American Indian (the current American Indian migrants from 10-15,000 years ago, not the earlier, non-American Indian migrants). What was different? Simple: they had better hunting technology and methods than earlier groups. Likewise for hunters in Europe and Asia in the same time period. Everywhere modern humans showed up with their latest hunting techniques, large animals disappeared; this was especially true in areas where humans were new arrivals: Australia, New Zealand, and Madagascar, for instance.

The fact is that these large, cold weather adapted mammals had survived numerous warm interglacial periods before, without going extinct. The difference then in those earlier interglacial periods was that either man did not yet exist, or later, man existed but did not have the very efficient tools and methods he would eventually develop about 15,000 years ago, or so. Without these, the mammoths and other large animals would still be around, because parts of North America, Northern Europe, and North Asia (Siberia) still resemble the climate and ecology which these animals inhabited during the ice ages; the only difference during the interglacial periods is that these ecological zones move northward. Mankind's better hunting skills were not going to make these animals extinct (necessarily) during the ice age, but during the difficult transition from ice age to interglacial period, the greater hunting skills of humans would have been enough to push several species into extinction when they were most vulnerable. Had ancient man had some kind of modern land management system (get your hunting license to hunt mammoth, etc.), then these animals would still be around. Instead, man overhunted them until they were gone (because they were easier to hunt or had more meat), and then switched to other species which were not as easy to hunt (and did not have as much meat) but which were better suited to survive man's predations.

And no one should buy this guy's "disease" argument. Where is the evidence that any large animal species was ever made extinct by disease? Sure, introduced diseases wiped out large numbers of American Indians, but they did not go extinct. They eventually developed resistence to these diseases, and survived. Animals are the same, and they do not live in large cities or other overpopulated clusters (unless domesticated by humans), so they are much less vulnerable to epidemics. This "theory" is nonsense, designed to deny the obvious effect that humans had on their environment; these politically correct types want you to believe that "environmental damage" is something that only rich white guys with modern technology are capable of doing. Rubbish. Mankind has been doing "environmental damage" ever since he discovered fire. It's an inevitable byproduct of human improvement; on the whole it was worth the price. No doubt some of the greenie-weenies disagree with me.

Molly Ivins will tell you with authority, that is was the Republicans. What this author doesn't tell us is that the passing of the mammoths and other behemoths had a significantly more negative effect on blacks, minorities, the handicapped, and homosexuals than it did on the evil white Europeans who caused the disaster. I think the Times ran a series of front page articles to prove this and that the did contain several facts.

Around 1110, in England, there was a very strange disease that killed all kinds of mammals and birds. No one knows what it was and it doesn't sound like any known disease. I read about it in an old book I have. Perhaps it was the same disease that caused the last mass extinction.

Yes, but did this disease cause any species to go extinct? That's the proof you'd need to give this theory any credence at all.

Frankly, this theory is bonkers. Cross-species infection is very rare; I've never heard of humans infecting wild, non-domesticated animals. The only wild animals ancient man would have had contact with would have been animals he killed and ate - it's kinda hard to spread a disease from man to wild animal population that way, would you not agree?

Of course domesticated animals sometimes cross-species infect humans (for example domesticated pigs can spread new flu varieties to humans). But humans infecting wild animals populations: I'd need to see demonstrable proof that this has actually happened in the past. Then I'd need to see demonstrable proof that in the past a disease had once wiped out an entire species. Even if there is proof of both, this theory is a long shot at best.

Molly Ivins will tell you with authority, that is was the Republicans. What this author doesn't tell us is that the passing of the mammoths and other behemoths had a significantly more negative effect on blacks, minorities, the handicapped, and homosexuals than it did on the evil white Europeans who caused the disaster. I think the Times ran a series of front page articles to prove this and that the did contain several facts.

Nonsense. Everyone knows that the Republican symbol is the elephant. A mammoth is simply a hairy elephant adapted for cold climates. Political cartoonists often portray very reactionary or very old fashioned Republicans as woolly mammoths. Why would Republicans kill off one of their own? And has anyone checked Molly Ivans' freezer to see if she is hoarding any mammoth steaks?

Actually, Spaniards did penetrate the Continental US. We had them all the way up into central-eastern Oregon, on gold explorations. They also made pretty secure footholds in the Southwestern US areas, and certainly in California... and it was all done fairly early on (1700's for Oregon)

In one of my favorite episodes of The Simpsons, Homer has a time machine and travels back to the time of the dinosaurs and sneezes and watches one dinosaur after another catch his cold and keel over dead. Wow... I love that show. It contains all truth.

Even if it were a disease, there's no evidence that humans introduced it. He made a good case himself for mosquitos as a culprit.

Again, where is the evidence for diseases making species go extinct? To argue this one would have to ignore the capacity for species to develop increased immunity to diseases.

More blame human garbage.

It's not "blame human garbage" if we humans actually did it (hunted certain animals to extinction, that is). I don't see why acknowledgement of the truth has to be avoided simply because it might be misinterpreted by some people with bad political motivations.

One guy shows up and passes the disease on to a ground sloth. The ground sloth takes it back to his den and infects his mate and any other ground sloths. They, in turn, infect yet other ground sloths.

Maybe the disease can be carried by a native North American bird that pecks at dung piles dropped by giant ground sloths. The bird then passes the disease to other giant ground sloths, and eventually they all get the disease.

I know it's difficult to think about such a complex process as a multi-species epidemic, but it happens. The best studied system involves human beings, pigs and birds, all living in China. They pass influenza back and forth, species to species, and every now and then create killer flu.

Oh, good one, I forgot about Madagascar. They said there was a lemur there the size of a gorilla. Went extinct. When? Around the time man arrived there.

Yes; there was also a giant flightless bird in Madagascar (similar in size to New Zealand's Moa, but thicker and heavier), and it went extinct shortly after the arrival of man, as well. Interestingly the original human colonizers of Madagascar were distantly related to the Polynesians who settled Hawaii, Polynesia, and New Zealand. They migrated to Madagascar traveling along the islands of the Indian ocean which lie between Africa and India.

I know it's difficult to think about such a complex process as a multi-species epidemic, but it happens. The best studied system involves human beings, pigs and birds, all living in China. They pass influenza back and forth, species to species, and every now and then create killer flu.

Yes, this is the perfect example which does not apply to the theory in question. Humans in China live in very densely populated areas, close together with their domesticated animals, and this fact allows them to pass diseases to each other. This does not apply to animals living in the wild, animals who also are too spread apart and thinly populated to quickly pass a disease, and thus create a contagion within their own species, assuming they are even capable of being infected by the cross-species disease in question. It's a very weak theory. And again, where is the species made extinct by a disease?

Occam's Razor applies. The simplist answer is human predation. And it's been proved; there is an example. Think Dodo.

Of course when it comes to the human mind, in practice, Occam's Razor is often powerless against the combined forces of human self-interest and self-deception. Both the politically correct leftists and some "conservatives" have strong political motivations for denying that ancient mankind could have exterminated entire species.

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